Integrated circuits and especially battery powered integrated circuits are expected to apply aggressive power saving techniques. A commonly used power saving technique involves shutting down (when operating in a so-called sleep mode) certain circuits such as high frequency clocks, phase locked loops and the like.
The circuits that remain active during this sleep mode are expected to perform various functions. For example, operating devices demand accurate tick times. A Common tick time is 1 Mili-Second (mSec). In some known devices a sleep clock is active during the sleep mode which generates a sleep clock signal that has a frequency of 32.768 Khz. Accordingly, the sleep clock signal has a sleep cycle of 30.5 usec. This sleep cycle defines the accuracy of the tick clock and this accuracy may not suffice.